The present invention concerns a hot-melt adhesive applicator, in particular a hot-melt adhesive applicator in gun form. Devices of that kind with mains voltage-operated heating units in a manually actuable gun housing provided with an advance unit for solid adhesive bars to be heated (therefore often also referred to as a xe2x80x98heating adhesive applicatorxe2x80x99) have long been known from the state of the art, but they suffer from a series of disadvantages: thus the voltage connection which is permanently necessary, for example by means of a mains cable, gives rise to difficulty in terms of free handling of the adhesive gun, conventional adhesives to be melted in solid bar form are limited in respect of their range of uses, and in particular simultaneous heating of the adhesive which is to be caused to melt for use thereof is often inadequate, by virtue of the structural implementations of the known heating device.
A hot-melt adhesive applicator is known from WO 89/10324.
In addition EP 0 385 235 A1 describes a hot-melt adhesive applicator in the form of a hot-melt adhesive applicator which is designed in the shape of a gun and which, for heating a hot-melt adhesive bar, has a plurality of separately operable heating elements in the form of PCT resistors, operation of the heating elements being effected in dependence on a temperature regulating circuit. A plurality of heating elements are also described in the hot-melt adhesive applicator known from DE 33 16 863 A1, in which case also an adhesive bar, under suitable actuation, can be liquefied.
Therefore the object of the present invention is to make a known hot-melt adhesive applicator more flexible in terms of its handling and use options, and in particular also to make it suitable for adhesives of the most widely varying kinds and with varying melting properties, and in addition to improve the electrical safety of known devices.
The foregoing object is attained by the hot-melt adhesive applicator comprising a hot-melt adhesive applicator comprising a manually handleable applicator unit which is adapted for electrically heating a replaceably insertable adhesive container, in particular for adhesive which can be liquefied by the action of heat, and which has a heating unit comprising a material of a predetermined heat capacity, which is provided for the transfer of heat to the adhesive container and which affords a contact surface for heat transfer and which has an electrical heating element, and a support module which is adapted to act on the heating element with an electrical voltage in a fitted holding condition of the applicator unit and which is so designed that the heating element can be supplied with voltage only in the holding condition and not in an operative adhesive application condition of the applicator unit of being detached from the support module. The method of the present invention comprises the steps of claim 9.
Thus, in an advantageous manner in accordance with the invention, the applicator unit which can be detached from the support module permits completely cable-free or connection-free handling of the heating module which is preferably provided with a pistol-like grip, so that not only is it possible to reach locations which involve a difficult access, but it is also possible to avoid potential risks arising due to the presence of an electrical power supply cable at the location of use.
The fact that the handle or grip unit is releasable in a further development of the invention also permits easy replacement of consumed adhesive containers which in a further preferred feature can be present in cartridge form and, by virtue of the structural configuration of the heating unit, in the form of a profile member, can be provided with optimised efficient input of heat. The coding of adhesive cartridges and heating module, which is provided in accordance with a development of the invention, permits in a particularly advantageous manner a further enhancement in the flexibility of the options of use involved, by virtue of a specific design configuration or setting of heating modules for specific adhesives, in particular in regard to any, especially required melting and operating temperatures, without the possibility of incorrect associations in practical alternate operation.
The temperature switch which is provided in accordance with a further developments permit activation or deactivation of the heating unit in dependence on an actual (observed) temperature so that by specifically and targetedly switching on additional heating power at measured temperatures below an operating temperature it is possible to minimise detrimental delays due to long heating times.
The brightness control unit which is provided in accordance with a development of the invention also eliminates the disadvantageous consequences of devices which are kept in a heating mode of operation over a long period of time (that is to say for example overnight), both in regard to a worsening quality of adhesive and also in terms of electrical power consumption.